Determining ethnic-, gender-, and age-specific waist circumference cut-off points to predict metabolic syndrome: the Sympathetic Activity and Ambulatory Blood Pressure in Africans (SABPA) study

Objective: The aim was to determine receiver-operating characteristic (ROC) waist circumference (WC) cut-off points best associated with metabolic syndrome (MetS) in a cohort of South African teachers. Design: Target population study. Setting and subjects: Four hundred and nine urban black (Africans) and white (Caucasians) from the Kenneth Kaunda district in North West province, between the ages of 25 and 65 years old, were stratified according to gender and age (25-45 years and 46-65 years). Outcome measures: Anthropometric, fasting overnight urine and biological markers for MetS. Results: ROC analysis determined pathological WC cut-off points of 91 cm for African men and 84 cm for African women. It is recommended that WC cut-off points should be 97 cm for Caucasian men and 84 cm for Caucasian women. Pathological WC cut-off points significantly predicted MetS in all ethnic-, gender- and age- specific groups, especially in male groups, with odds ratios of 7.6 [95% confidence interval (CI): 3.4-17.1, p-value = 0.00) for African men and 6 (95% CI: 3-12.1, p-value = 0.00) for Caucasian men. Conclusion: ROC-developed WC cut-off points were found to be good predictors of MetS in a South African cohort, especially in the men. Further research in prospective cohort studies is warranted to verify our findings.